Method for controlling fluid flow to and from an eye during ophthalmic surgery

ABSTRACT

A method and apparatus provided for controlling fluid control to and from an eye or a phacoemulsification handpiece. The handpiece includes an ultrasonically driven, hollow, sleeved needle and the method includes inserting the needle and sleeve into an eye for phacoemulsification of eye tissue and introducing fluid into the eye through an annulus established between the sleeve and the needle. Aspiration of fragmented tissue and fluid from the eye is conducted through the hollow needle. An initial irrigation fluid pressure is determined and the irrigation fluid flow and aspiration fluid flow are adjusted based upon the initial determination. Thereafter continued determination of irrigation fluid pressure is utilized to continuously adjust irrigation fluid flow and/or aspiration fluid flow.

[0001] The present invention generally relates to a method and apparatusfor ophthalmic surgery. More specifically, the present invention isdirected to a method and apparatus for controlling fluid flow to andfrom an eye during ophthalmic surgery.

[0002] In retinal and vitreous surgery, a separate needle used to supplyinfusion, or irrigation, fluid or suction, for aspiration, respectively.

[0003] Phacoemulsification procedures typically include the use of ahandpiece for inserting a sleeved needle through a corneal incision andthereafter vibrating the needle in order to emulsify hard nuclearmaterial of the cataract lens. The incision is generally made in theregion of the limbus or in the cornea.

[0004] An annulus formed between the sleeve and the needle functions asa passage which allows for the introduction, or inflow, of the salinefluid into the eye for irrigation.

[0005] The saline fluid prevents the cornea from collapsing as the lensmaterial is emulsified and aspirated. In addition, the saline irrigationfluid aids in the aspiration of emulsified cataract lens material fromthe eye. The aspiration is conducted through the hollow center of thevibrating needle. The handpiece and needle are connected with anexternal power source, an irrigation fluid source, and a vacuum source.A control system provides for coordinated ultrasonic vibration,irrigation and aspiration of fluids to and from the eye.

[0006] Heretofore, irrigation fluid pressure has been establishedthrough the use of an elevated bottle, which provides a source of salinesolution. It should be appreciated that fluid control and eye pressureare of utmost importance. Corresponding irrigation and aspiration offlow rates as hereinabove noted are used to maintained the eye in aninflated, pressurized condition during cataract removal. However, theincision size is important since it provides an alternate route forleakage of fluid from the eye.

[0007] This leakage causes diminished inflation of the eye duringcataract surgery and occurs between the edges of the incision andexterior surfaces of sleeved needle. During the phacoemulsificationprocedure, the needle is manipulated and such manipulation can lead towound stretching. This, in turn, changes the leakage rate from the eyeand compounds the problem of balanced irrigation and aspiration fluidflow and the maintenance of a proper pressure state of the eye duringsurgery.

[0008] Accordingly, variation in wound construction, sleeve/incisiongeometry and needle size are important as they relate to fluid leakagefrom the wound. Deflation of the eye, which may be caused by suchleakage, may cause certain tissue within the eye to collapse within oneanother or on the sleeved needle extending into the eye. In this manner,fluid loss may cause damage to the cornea, iris, or lens capsule whichsurround the cataract.

[0009] One method for counteracting fluid leakages as to increase theamount of irrigation and aspiration fluid flow which is inconvenientlydone through raising and lowering of the irrigation source bottle alongwith a concomitant adjustment in aspiration rate.

[0010] Accordingly, there is a need for a system for coordinatingirrigation fluid flow and aspiration flow during ophthalmology surgeryprocedures. The present invention fills that need.

SUMMARY OF THE INVENTION

[0011] A method for controlling fluid flow to and from an eye duringophthalmic surgery includes introducing irrigation fluid into an eye andaspirating fluid from the eye. During fluid flow initial irrigationfluid pressure is determined. Irrigation fluid flow, aspiration fluidflow and maximum vacuum is adjusted based on the determined initialirrigation fluid pressure. Thereafter irrigation fluid pressure iscontinuously determined and irrigation fluid flow, aspiration fluid flowand maximum vacuum is continuously adjusted based on the continuousdetermination of irrigation fluid pressure.

[0012] A handpiece suitable for use in phacoemulsification procedureswhile producing the method of the present invention, generally includesan ultrasonically driven, hollow, sleeved needle and the method, inaccordance with the present invention, further includes the steps ofinserting the needle and sleeve into an eye for phacoemulsification ofeye tissue. Irrigation fluid is introduced into the eye through anannulus established between the sleeve and the needle and fluid isaspirated from the eye through the hollow needle.

[0013] An initial irrigation fluid pressure is determined and inresponse thereto irrigation fluid flow and aspiration fluid flow areadjusted in order to initially maintain proper eye pressure within theeye.

[0014] Thereafter, irrigation pressure is continuously determined and inresponse thereto, the irrigation flow and aspiration fluid flow areadjusted based upon the continuous determination of irrigation fluidpressure. Importantly, the method does not include the raising andlowering of a bottle of irrigation fluid as is necessary in prior artmethods. The present invention is also distinguished from prior artmethod in that the fluid flow rates are automatically regulated, oradjusted based upon irrigation fluid pressure determination. This is tobe distinguished from current method in which control of irrigationfluid is maintained by feedback from a surgeon based upon visualobservation of tissue under the affects of irrigation. In addition, thesurgeon control of irrigation is limited to an on/off control valve andadjustment of the irrigation fluid source height.

[0015] In the present invention, the introduction of irrigation fluidinto an eye is performed through the use of a positive displacement pumpand the step of adjusting the irrigation fluid flow includes adjustingthe pump speed.

[0016] The determination of irrigation fluid pressure many be donethrough the use of a transducer disposed in a line interconnecting thepump and handpiece or through direct measurement of pressure within theeye.

[0017] The adjustment of aspiration fluid flow may include setting amaximum aspiration vacuum pressure as a function of determinedirrigation fluid pressure. More particularly, this maximizes aspirationvacuum may be a linear function of the determined irrigation fluidpressure.

[0018] The change of irrigation fluid pressure may also be utilized inaccordance with the present invention for providing an indication ofwound leaking.

[0019] The apparatus in accordance with the present invention forcontrolling fluid flow to and from a phacoemulsification handpiece inorder to accommodate changes in incision size and would stretchingduring eye surgery generally includes a supply of irrigation fluid and apositive displacement pump for introducing irrigation fluid from thesupply of irrigation fluid into an eye through an annulus establishedbetween a sleeve and a needle of a handpiece.

[0020] A vacuum source is provided for aspirating fluid from the eyethrough the hollow portion of the needle and a pressure sensor isprovided for determining pressure of irrigation fluid introduced intothe eye.

[0021] A control system is provided for adjusting irrigation fluid andthe aspiration fluid flow rates in response to the determined irrigationflow pressure. More particularly, the pressure sensor may be disposed ina line interconnecting the positive displacement pump in the needle or apressure sensor disposed in the eye.

[0022] The control system may also include an indication for enablingmonitoring by a surgeon of wound construction consistency based uponirrigation of fluid pressure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention may be more clearly understood withreference to the following detailed description, in connection with theappended drawings, in which:

[0024]FIG. 1 is a diagram illustrating apparatus and method inaccordance with the present invention; and

[0025]FIG. 2 is a plot of maximum stable vacuum corresponding tomeasured irrigation pressure which may be utilized by the control systemshown in FIG. 1 for making fluid flow changes.

DETAILED DESCRIPTION

[0026] With reference to FIG. 1, there is shown apparatus 10 inaccordance with the present invention for controlling fluid flow to andfrom a phacoemulsification handpiece 12 which generally includes asupply 14 of irrigation fluid, a positive displacement pump 16, a vacuumsource 18, a pressure sensor 20 and a control system 22 describedhereinafter in greater detail and also suitable for performing themethod of the present invention.

[0027] It should be appreciated that while a phacoemulsificationhandpiece 12 is described herein for the practice of the presentinvention, for illustration purposes, other surgical instruments (notshown) may be utilized for different ophthalmic surgical procedures andseparate infusion and aspiration needles (not shown) may be used forpractice of the present invention.

[0028] The handpiece 12, which may be of any conventional type, includesan ultrasonically driven, hollow needle 24 having a sleeve 26 thereaboutwhich establishes an annulus 30 round needle for introducing irrigationfluid into an eye 34 in a conventional manner.

[0029] By utilizing the pump 16 which preferably is a positivedisplacement pump in combination with the pressure sensor 20, a “closed”pressure measurement system is provided which enables the precisecontrol of infusion pressure into the eye without relying on the heightof a traditional irrigation fluid source (not shown). Preferably abi-directional positive displacement pump 16 facilitates precise controlof the fluid pressure.

[0030] The control system 22 provides electrical power to the handpiece12 for ultrasonically driving the needle 24 through line 38. Throughlines 40, 42 the control system 22 controls the pump 16 speed and avacuum source 18 respectively. The aspiration vacuum source 18 may be ofany conventional type and include as, for example, a peristaltic pump.Input to the control system 22 from the sensor 20 is provided through aline 46 or a line 48 from a sensor (not shown) disposed within the eye.

[0031] The sensor 20 is disposed in an irrigation line 52 between thepump 16 and the handpiece 12. Aspiration from the handpiece 12 andhollow needle 24 to the vacuum source 18 occurs through the line 54.

[0032] The pressure transducer 20 may be on medical grade compensatedsensor pressure which is available from Motorola. Alternatively directirrigation fluid pressure measurement may be made by a transducerdirectly from the eye. A suitable transducer for this mode of operation,is also which is available from Motorola. The control system 20 includessoftware for conducting the function and method of the apparatus ashereinafter described.

[0033] A method for controlling fluid flow to and from aphacoemulsification handpiece 12 in order accommodate changes inincision size and wound stretching, for example, during eye surgery,generally includes a step of inserting the needle 24 into the eye forphacoemulsification of eye tissue. Irrigation fluid is introduced intothe eye through the annulus 30 established between the sleeve 26 and theneedle 24. Aspiration of the fluid from the eye 34 is then conductedthrough the hollow needle handpiece 12 and line 54 to the aspirationvacuum source 18.

[0034] An initial irrigation fluid pressure is determined by the sensor20 and the irrigation fluid flow from the source 14 is adjusted by thecontrol system 22 through operation of pump 16 based upon a determinedinitial irrigation fluid pressure as provided by the sensor 20.

[0035] Thereafter, the irrigation fluid pressure is continuouslydetermined via the sensor 20 and the irrigation fluid flow andaspiration fluid flow based upon this continuous determination ofirrigation fluid pressure is provided by the control system through thelines 40,42 respectively to the pump 16 aspiration vacuum source 18.

[0036] A variation in wound construction, sleeve/incision geometry andneedle size are then mediated by monitoring the pressure present ateither the surgical site or the sensor 20. A leaking wound can becompensated for by adjustment of fluid flow by the control system 22.

[0037] It has been found that maximum usable vacuum is a function ofirrigation fluid pressure. This relationship is shown in FIG. 2. In FIG.2, the data shows a clear trend of increased usable vacuum with anincreased irrigation pressure. This data is derived from variouscombinations of sleeves, needles and incision sizes in a laboratorymodel (not shown).

[0038] This relationship can be incorporated as an algorithm in thecontrol system 22 software. Accordingly, the control system 22 canprovide a maximum vacuum setting shown on the Y axis on the plot shownon FIG. 1 as a basis of a measured irrigation pressure. In addition, thecontrol system 22 may include an indicator 60 which may be visible oraudible for enabling a surgeon to monitor wound construction consistencybased upon monitoring of irrigation fluid pressure, and changes theretoduring phacoemulsification procedures.

[0039] Although there has been hereinabove described a method andapparatus for controlling fluid flow to and from an eye orphacoemulsification handpiece in accordance with the present invention,for the purpose of illustrating the manner in which the invention may beused to advantage, it should be appreciated that the invention is notlimited thereto. Accordingly, any and all modifications, variations andequivalent arrangement which may occur to those skilled in the artshould be considered to be within the scope of the present invention asdefined in the appended claims.

What is claimed is:
 1. A method for controlling fluid flow to and froman eye during ophthalmic surgery, said method composing the steps of:introducing irrigation fluid into an eye; determining initial irrigationfluid pressure; adjusting irrigation fluid flow based on the determinedinitial irrigation fluid pressure; continuously determining irrigationfluid pressure after the initial determination; and continuouslyadjusting irrigation fluid flow based on the continuous determination ofirrigation fluid pressure.
 2. A method for controlling fluid flow to andfrom an eye during ophthalmic surgery, said method composing the stepsof: introducing irrigation fluid into an eye; determining initialirrigation fluid pressure; adjusting aspiration fluid flow based on thedetermined initial irrigation fluid pressure; continuously determiningirrigation fluid pressure after the initial determination; andcontinuously adjusting aspiration fluid flow based on the continuousdetermination of irrigation fluid pressure.
 3. A method for controllingfluid flow to and from an eye during ophthalmic surgery, said methodcomposing the steps of: introducing irrigation fluid into an eye;determining initial irrigation fluid pressure; adjusting maximum vacuumsetting based on the determined initial irrigation fluid pressure;continuously determining irrigation fluid pressure after the initialdetermination; and continuously adjusting maximum vacuum setting basedon the continuous determination of irrigation fluid pressure.
 4. Themethod according to claim 1 further comprising the step of using apositive displacement pump to introduce the irrigation fluid and thestep of adjusting irrigation fluid flow includes adjusting pump speed.5. The method according to any one of claims 1, 2 or 3 where the step ofinitially determining irrigation fluid pressure and continuouslymeasuring irrigation fluid pressure includes determining in-lineirrigation pressure.
 6. The method according to claim 2 wherein the stepof adjusting aspiration fluid flow includes setting a maximum aspirationvacuum pressure as a function of determined irrigation fluid pressure.7. The method according to claim 6 wherein the function is linear. 8.The method according to any one of claims 1, 2 or 3 further comprisingthe step of using a change in irrigation fluid pressure to provide anindication of wound leaking.
 9. A method for controlling fluid flow toand from a phacoemulsification handpiece, the handpiece including anultrasonically driven, hollow needle, said method comprising the stepsof: inserting the needle into an eye for phacoemulsification of eyetissue; introducing irrigation fluid into the eye; aspirating fluid fromthe eye through the hollow needle; determining initial irrigation fluidpressure; adjusting irrigation fluid flow and aspiration fluid flowbased on the determined initial irrigation fluid pressure; continuouslydetermining irrigation fluid pressure after the initial determination;and continuously adjusting irrigation fluid flow and aspiration fluidflow based on the continuous determination of irrigation fluid pressurein order to accommodate changes in needle incision size and woundstretching during eye surgery.
 10. The method according to claim 9further comprising the step of using a positive displacement pump tointroduce the irrigation fluid and the step of adjusting irrigationfluid flow includes adjusting pump speed.
 11. The method according toclaim 10 wherein the steps of initially determining irrigation fluidpressure and continuously measuring irrigation fluid pressure includingdetermining in-line irrigation pressure.
 12. The method according toclaim 9 wherein the step of adjusting aspiration fluid flow includessetting a maximum aspiration vacuum pressure as a function of determinedirrigation fluid pressure.
 13. The method according to claim 12 whereinthe function is linear.
 14. The method according to claim 9 furthercomprising the step of using a change in irrigation fluid pressure toprovide an indication of wound leaking.
 15. Apparatus for controllingfluid flow to and from an eye, said apparatus comprising: a supply ofirrigation fluid; a positive displacement pump for introducingirrigation fluid from said supply of irrigation fluid into an eye; avacuum source for aspirating fluid from the eye through a hollow needle;a pressure sensor for determining pressure of irrigation fluidintroduced into the eye; and a control system for adjusting irrigationfluid and aspiration fluid flow rates in response to determinedirrigation fluid pressure.
 16. The apparatus according to claim 15wherein said pressure sensor is disposed in a line interconnection, saidpositive displacement pump and the needle.
 17. The apparatus accordingto claim 15 where said pressure sensor is disposed in the eye.
 18. Theapparatus according to claim 15 wherein said control system includes anindicator for enabling monitoring by a surgeon of wound constrictionconsistency based upon irrigation fluid pressure.
 19. The methodaccording to claim 12 wherein the function is linear.
 20. The methodaccording to claim 9 further comprising the step of using a change inirrigation fluid pressure to provide an indication of wound leaking. 21.Apparatus for controlling fluid flow to and from an eye, said apparatuscomprising: a supply of irrigation fluid; a positive displacement pumpfor introducing irrigation fluid from said supply of irrigation fluidinto an eye; a vacuum source for aspirating fluid from the eye through ahollow needle; a pressure sensor for determining pressure of irrigationfluid introduced into the eye; and a control system for adjustingirrigation fluid and aspiration fluid flow rates in response todetermined irrigation fluid pressure.
 22. The apparatus according toclaim 15 wherein said pressure sensor is disposed in a lineinterconnection, said positive displacement pump and the needle.